Aarhus Psychiatric hospital has one of the largest brain collections in the world – it is housing 9479 brains. Most of the brains came from the deceased patients diagnosed with schizophrenia, dementia, manias, major depression and bi-polar disorder - the patients that haven't been treated with modern medical methods. This is very useful for researching the effects of the modern treatments on the human brain.
This institution was established in Denmark in 1945, with the aim to learn as much as possible from the brains of the mentally ill. Each collected brain was thoroughly examined and properly documented, including the full medical records of the patients. The brains are sliced and the specific brain regions are preserved in paraffin or by using other techniques.
This vast amount of samples serves as immensely helpful data for neuropathologists. The collection of the brains was going on until 1982, when it was decided that it is unethical to collect the brains from the deceased patients without their or their families' permission.
Unfortunately, the collection is not open to the wide public, however, if you are a scientist in the field, it is possible to get a permit to see it or to request a tissue.